The invention relates to a a gas discharge structure, in particular for laser waveguides, which structure exhibits a two-dimensionally extending gas discharge and comprises a pair of electrodes including a first and a second electrode which have mutually facing electrode surfaces, a gas discharge space arranged between the electrode surfaces with a plasma gas provided therein and a high frequency source with which a current can be fed into the pair of electrodes for producing a plasma between the first and the second electrode.
Gas discharge structures of this type form the subject matter for example of DE 37 29 053, DE 38 28 952 or DE 38 28 951.
In order to attain greater powers in gas discharge structures of this type which are utilised in laser waveguides where large electrode surfaces are required, problems arise since, when using large electrode surfaces, the discharge for the excitation of the plasma forming gas, referred to hereinafter as a plasma gas, exhibits a wavelength dependent spatial modulation of the electrical field strength in the gas discharge space when there is an excitation using high frequency current in the UHF range, preferably in the range of approximately 100 MHz or more.
Field strength modulations of this type may, for example, as is known from the U.S. Pat. Nos. 4,169,251 or 4,352,188, be compensated to some extent by inductances disposed at the edges of the electrodes or by external networks, whereby the arrangement of these inductances and the matching thereof is expensive and also varies from case to case, for example, with the parameters of the gas discharge and the power being coupled-in, so that a renewed matching of the inductances is in many cases necessary when there is an alteration of just a single parameter.
A further possibility of making the gas discharge more homogeneous, which is known from the U.S. Pat. No. 4,751,717, consists in the multiple supply of the high frequency power, distributed over the discharge structure, but this too is very expensive.